ML19289F543

LER 79-066/03L-0 on 790506:narrow Range Level Transmitter LT-496 in L Steam Generator Read Erratically.Channel Inoperable.Probable Cause Was Drain Lines Off Both High & Low Pressure Sides of Transmitter.Lines Capped

ML19289F543
Person / Time
Site:	North Anna
Issue date:	06/04/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19289F541	List: ML19289F540 ML19289F543 ML19289F544
References
LER-79-066-03L, LER-79-66-3L, NUDOCS 7906110160
Download: ML19289F543 (2)

Text

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14 15 HEPOH T DATE 80 EVENT DESCRIPTION AND PROBAOLE CONSEQUENCES o 2 l During normal flode 1 operation, indication from the narrc>w range level transmitter i o 3  ; LT-496 for "C" steam generator was noted to be reading erratically. This channel l o 4 lwas declared inoperable and was placed in a tripped condition as per action statement l o s  ; #4, Table 3.3-3, of T.S. 3.3.2-1. The two remaining channels were functional; there- l o 6 I fore, the health and safety of the general public was not affected. This event is I o 7 l reportable as per T.S. 6.9.1.9.b. l o H l 1 7 8 3 80 SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SU8 CODE COMPONENTCODE SU3 CODE SU8 CODE O 9 l H l B l@ [E.j@ [B_j @ VlAl LlVlE lX l @ l_EJ @ l_DJ @

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Attachment:

Page 1 of 1 Docket No: 50-338 Report No.: 79-066/03L-0 Description of Event During Mode 1 operation after an extended outage, the level indicator for level transmitter LT-496 was noted to be reading erratically. The effecteo channel was placed in a tripped condition as per action statement #4 of table

3. 3-3 o f T.S . 3. 3. 2.1.

Probable Consequenca of Occurrence The engineered safety feature actuation system required by T.S. 3.3.2.1 is provided to initiate automatic protective actions in the event of an accident.

In this case, the steam generator level channels are used to initiate the actions described by table 3.3-3 sections 5 and 6 of T.S. 3.3.2.1.

Placing the affected channel in a tripped condition changes the protective action coincidence from the normal 2 out of 3 to a more conservative 1 out of 2.

The health and safety of the general public is not affected. There are no generic implications.

Cause The cause for the erratic indication from LT-496 was steam leaks on both the high and low pressure side drain lines on the transmitter.

Immediate Corrective Actions Placed the associated level channel in a tripped condition as per action statement #4 of T.S. 3.3.2.1.

Scheduled Corrective Action Capped the two suspected drain lines during a subsequent shutdown. This did reduce the magnitude of the oscillation. Returned LT-496 to service.

Action Taken To Prevent Recurrence The exact cause of the oscillation is still under investigation.

2230 549